Ministers appear to have failed to hand a crucial report about the work capability assessment – warning it put at risk the lives of thousands of people with mental health conditions – to the expert they commissioned to review the test.

An investigation by Disability News Service (DNS) suggests that work and pensions secretary Iain Duncan Smith (pictured) and employment minister Chris Grayling neglected to pass on a legal letter written by a coroner in the wake of the suicide of a disabled man, Stephen Carre, in 2010.

The letter – written under Rule 43 of the Coroner’s Rules – said Carre’s death had been triggered by being found “fit for work”, and it called for a review of the policy not to seek further medical evidence from a GP or psychiatrist if a claimant has a mental health condition.

A coroner could only write a Rule 43 letter – a system replaced in 2013 – if he or she believed that the evidence they heard in an inquest “gives rise to a concern that circumstances creating a risk of other deaths will occur or will continue to exist in the future”.

It is the second letter uncovered by DNS to have been written by a coroner to warn about the failure to seek further medical evidence when assessing the fitness for work of someone with a mental health condition, and was written more than three years before a similar report into the death of Michael O’Sullivan, from north London.

Although the Rule 43 letter relating to Stephen Carre was sent to the Labour work and pensions secretary, Yvette Cooper, it arrived on 30 March, just a few days before the start of the 2010 general election campaign.

Rule 43 gave ministers 56 days to respond to the letter, but nothing – apart from what is believed to have been a holding reply by the department’s permanent secretary on 4 May 2010 – had been sent to the coroner by October 2010, five months after Duncan Smith and Grayling had taken up their posts in the Department for Work and Pensions (DWP).

And the letter does not appear to have been passed by ministers to Professor Malcolm Harrington, who was appointed by Grayling to review the “fairness and effectiveness” of the WCA for the government in late June 2010.

Harrington has told DNS that he believes he was not shown the coroner’s report.

He said: “I cannot recall the report. Nobody brought it to my attention that I can remember.

“If I had known about that coroner’s report, I would have said that this was something else we need to look at.

“I am a doctor, I know about coroner’s reports. Coroner’s reports are something that you don’t ignore.”

He said the need to secure further medical evidence was a consistent concern during the three reviews he carried out, and he made it clear in his third – a recommendation that has still not been implemented by the government, three years later – that decision-makers should “actively” consider seeking further medical evidence.

He said that, if he had been shown the coroner’s letter, it would almost certainly have led to him making recommendations far earlier about the need to seek further medical evidence.

He said this was particularly important for claimants with mental health conditions, like Stephen Carre.

He said: “Of course! They weren’t picking up this additional information that should have been right up front. It would have brought forward the best evidence.”

Asked how he felt about Grayling’s apparent failure to pass on this information to him, he said: “No comment.”

Stephen Carre, who lived alone in Eaton Bray, Bedfordshire, had been found “fit for work” after an assessment by a doctor working for the government contractor Atos Healthcare, with the final decision that he was not eligible for out-of-work disability benefits – again, with no effort made to consult his doctor, psychiatrist or community psychiatric nurse – made by a DWP civil servant.

He took his own life in January 2010, just days after learning that a reconsideration of the decision, by DWP, had confirmed that he was “fit for work” and so not eligible for employment and support allowance (ESA), the out-of-work disability benefit launched by the Labour government in October 2008.

His father, Peter, told DNS that Atos, its assessor and DWP had all failed Stephen.

He said: “Anyone could have seen that Stephen was incapable of work. It is totally beyond me how they could have found him fit for work.

“If they had gone to his GP or his psychiatrist, I have no doubt the result of his assessment would have been different and he would probably still be with us today.”

The Ministry of Justice has confirmed that although it has a copy of the coroner’s report into the death of Stephen Carre, it has no record of a DWP response, even though DWP had a legal duty to respond to the report.

The office of the coroner who wrote the report, Tom Osborne, has not yet been able to confirm whether he received a response, because the relevant files are being retrieved from the archives.

But Harrington said: “If they didn’t respond, they are definitely in breach of the regulations.”

Despite the coroner’s letter, a DWP spokesman said: “Suicide is a tragic and complex issue and there are often many reasons why someone takes their life, so to link it to one event is misleading.”

The spokesman said that a response was sent to the coroner on 4 May 2010, but he has yet to confirm that this was merely an acknowledgement of the Rule 43 letter, or a holding response.

DNS has seen a letter sent to Peter Carre on 6 October 2010 in which the coroner said he had “yet to receive a substantive response” to his Rule 43 report from DWP.

Asked whether Grayling, who is now leader of the House of Commons, and Duncan Smith responded to the coroner’s letter and carried out the review of the issue raised by the coroner, he pointed to the five independent reviews of the WCA, carried out by Harrington and Paul Litchfield, and to the “significant improvements” made to the assessment since 2010.

He said these improvements included “improving the opportunities people have to present medical evidence”, and improvements to the process for people with mental health conditions, while he said the percentage of people with mental health conditions receiving the highest level of ESA support “has more than tripled since 2010”.

He said: “The WCA now has a much greater focus on what someone can do and on the impact of mental health conditions on someone’s capability to work.”

The DWP spokesman said claimants were “encouraged to provide all evidence that will be relevant to their case at the outset of the claim, including medical evidence supplied by their GP or other medical professionals”, while WCA assessors are “expected to seek further evidence” if it would help them award ESA without the need for a face-to-face assessment.

He said DWP decision-makers “assess all available evidence and seek more if required to reach their decision”.

But he admitted that DWP was still in discussions with Maximus – which took over the WCA contract from Atos earlier this year – to “pilot new evidence-seeking processes for claimants with mental health conditions”, more than five years after Stephen Carre’s death.

Asked whether Grayling and Duncan Smith were shown the letter, he said: “I don’t know. I can’t answer that question.”

He also claimed he did not know whether anyone in the press office had asked Duncan Smith about the coroner’s letter.

And asked whether the two ministers ensured that Harrington was shown the coroner’s letter, he said: “I’m not able to answer that. I don’t know the answer to that.

“What I do know is that Malcolm Harrington had access to a huge range of information. Whether he saw this one particular letter, I don’t know.”

In a written statement to questions from DNS, the spokesman declined to say whether Duncan Smith and Grayling would apologise to the families of Stephen Carre and Michael O’Sullivan.

Osborne’s Rule 43 letter emerged through a freedom of information request by DNS to the Ministry of Justice.

The request was submitted* after DNS uncovered a coroner’s report written in January 2014, following the death of Michael O’Sullivan, a father-of-two from north London, which said that the decision to take his own life had been triggered by being found fit for work.

Questions about the O’Sullivan case were raised twice last month at prime minister’s questions, by the SNP’s Westminster leader, Angus Robertson.

The O’Sullivan family said in a statement: “We would like to extend our sincere condolences to the Carre family and our sincere sympathies for their son, Stephen, whose untimely death mirrors our father’s in many tragic ways.

“Peter Carre has shown great resilience in reliving this tragedy in such a public manner.

“Having to relive our loss two years on has been very distressful and upsetting, but we felt that anything positive that could be learned from our father’s death was worth it.

“We stand by what we have always said, that the WCA is not a fit or a fair way to assess people with a mental health disability or any disability.

“It is heart-wrenching to hear that in 2010, three years before our father took his own life, Stephen Carre did the very same due to the cruel WCA.

“Had the DWP acted as it should have done in Mr Carre’s case, had it learned from its failings then, we firmly believe that our father’s death would have been preventable.

“Instead we are forced to spend another Christmas without our much-loved father. It is utterly devastating. Our family is shattered beyond repair.”

Atos refused to respond to requests for a comment.

*The Stephen Carre report did not emerge at the same time as the Michael O’Sullivan report because legislation was updated in 2013, which meant references to the two reports were filed in separate online locations by the Ministry of Justice. The post-2013 reports are available in full, but the Rule 43 reports are only available in summary